The Collaborative International Dictionary of English v.0.48:

Ridotto \Ri*dot"to\, n. [It., fr. LL. reductus a retreat. See
   Redoubt.]
   1. A favorite Italian public entertainment, consisting of
      music and dancing, -- held generally on fast eves.
      --Brande & C.
      [1913 Webster]

            There are to be ridottos at guinea tickets.
                                                  --Walpole.
      [1913 Webster]

   2. (Music) An arrangement or abridgment of a piece from the
      full score.
      [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Ridotto \Ri*dot"to\, v. i.
   To hold ridottos. [R.] --J. G. Cooper.
   [1913 Webster]